Apparatus for contacting two liquids of different specific weights



March 8, 1966 J. A. DE SMET 3,239,315

APPARATUS FOR CONTACTING TWO LIQUIDS 0F DIFFERENT SPECIFIC WEIGHTS FiledJan. 5, 1965 2 sheets-{sheet 1 F/Gi I I 4? f I E 3-- i 47 24 i i IS a ai 50 g 48 I a E/ i t I l7 4 I I 5 A INVENTOR JEAN ALBERT DE SMET BYewqlk ATTORNEYS J. A. DE SMET APPARATUS FOR CONTACTING TWO LIQUIDS OFDIFFERENT SPECIFIC WEIGHTS March 8, 1966 2 Sheets-Sheet 2 Filed Jan. 5,1965 m m m JEAN ALBERT DE SMET 0 BY mm M b \Mk ATTORNEYS United StatesPatent 3,239,315 APPARATUS FOR CGNTACTING TWO LIQUIDS OF DIFFERENTSPECIFIC WEIGHTS Jean Albert De Smet, Wilrijk, Belgium, assignor toExtraction De Smet, Edegem, Belgium, a Belgian company Filed Jan. 5,1965, Ser. No. 423,432 Claims priority, application: Luxembourg, Feb.18, 1960, 38,262; Dec. 29, 1964, 47,690 2 Claims. (Cl. 23-2705) overallcounter-current procedure is carried out.' The" procedure comprises aseries of operations of intimate mixing of two liquids within a seriesof compartments, each mixing operation being followed by a decantationoperation. While, when viewed overall, the procedure is counter-current,the two liquids move in the same direction through each of thecompartments involved in the apparatus.

The apparatus according to the invention may be utilized to providecontact between two liquids of different specific weights so as toprovide a process of solvent extraction. The apparatus comprises avessel having a series of compartments extending in longitudinaldirection and delimited by substantially parallel and horizontal plates.The vessel has four substantially vertical walls, two of said wallsextending in longitudinal direction, the two others extending intransverse direction. The plates extend to the longitudinal walls and toa point which is some distance from the transverse walls so as to leavea passage permitting liquid flow between the transverse edges of theplates and the transversal walls. The lower compartment and the uppercompartment have a discharge opening. The compartment which is situatedimmediately above the lower compartment as well as the compartment whichis situtated inunediately below the upper compartment has an inletopening. Each of the intermediate compartments contains a means formixing the liquids and for propelling the mixture through thecompartment. Said means are alternately arranged on one side and on theother side of the adjacent compartment. The mixing and propelling meansof the compartment which is immediately above the lower compartment issituated on the same side as the inlet opening of said compartment andthe mixing and propelling means of the compartment which is immediatelybelow the upper compartment is situtated on the same side as the inletopening of said compartment.

In an advantageous embodiment of the invention, the apparatus contains abafiie means for each of the intermediate compartments comprising ahorizontal partition extending in transverse direction, which isconnected to the transverse wall on the same side as the mixing andpropelling 'means and which extends into the compartment for a distancewhich is less than the distance from the transverse wall to the mixingand propelling means.

In a particular embodiment of the invention, the mixing and propellingmeans are comprised of shafts extending in transverse direction andhaving blades arranged in planes comprising the geometrical axis of theshaft.

In an especially preferred embodiment of the invention, the shaft isarranged in a chamber delimited by two vertical walls extending theWhole height of the compartment 3,239,315 Patented Mar. 8, 1966 andhaving a median slot extending in transverse direction, the portion ofthe wall which is provided on the compartment side and below the slotbeing offset towards the compartment with respect to the upper part ofthe same wall and having a flange which is bent towards the shaft.

Other details and particularities of the invention will be apparent fromthe description of an apparatus according to the invention, thedescription which is given being solely by way of non-limitative exampleand with reference to annexed drawings.

FIG. 1 is a diagrammatic vertical section of an apparatus according tothe invention.

FIG. 2 is a section along line 22 of FIG. 1.

FIG. 3 is a section along line 33 of FIG. 2.

In the various figures, the same reference numerals relate to identicalelements.

The apparatus shown in the figures is intended to contact two liquids ofdifferent specific weights, so as to carry out a procedure of solventextraction. While the apparatus can be employed in any case wherein anextracting liquid is used to extract some material from a conveyingliquid, the apparatus will be described with reference to the figures inconnection with the extraction of soaps from a miscella by means of analcohol. In the method of particular use of the apparatus, described byway of example, the conveying liquid is comprised of misceila, forexample of an oil or grease solution in hexane. This miscella alsocontains soaps which must be extracted. The material to be extractedthus comprises soaps, while the extracting liquid comprises dilutealcohol.

The apparatus comprises a vessel made up of a lower wall 1 which formsthe bottom, an upper wall 2, two transverse walls 3 and 4 and twolongitudinal walls 5 and 6. The vessel is divided into compartments byhorizontal plates 7 to 15. In FIG. 1, nine horizontal plates are shownbut it has to be understood that in practice the plant will generallycomprise a larger number of plates. Said plates are closely arranged,the distance between two adjacent plates being from 50 millimeters (mm.)to about mm. The distance between the lower wall 1 of the vessel and thelower plate 7 is also about 50 mm. to 100 mm. Also the distance betweenthe upper plate 15 and the upper wall 2 of the vessel is about 50 to 100mm. Each of the plates 7 to 15 extends to the longitudinal walls 5 and6, as may be seen from FIG. 2. Each of the plates 7 to 15 extends onlyto a point some distance from the transverse walls 3 and 4. This may beseen in FIG. 1. Between the transverse walls 3 and 4- of the vessel andthe transverse edges of the plates 7 to '15, i.e. the edges of saidplates which are parallel to the transverse walls 3 and 4, a passageremains free for the flow of the liquids. Each of the intermediateplates, i.e. plates 8 to 14, has at one end a downwardly oriented flange16 and at the other end an upwardly oriented flange 17. This flange 17is opposite to a downwardly orientated flange 16 of an adjacent plate.The sum of the heights of the flanges 16 and 17 is substantially lessthan the distance between two adjacent plates, so that a passage remainsfree between opposite flanges of adjacent plates.

The lower plate 7 has only an upwardly orientated flange 18 opposite thedownwardly orientated flange 16 of the plate 8. The upper plate 15 hasonly a downwardly orientated flange 19 opposite the upwardly orientatedflange 17 of the plate 14. Furthermore, the plate 15 extends to thetransverse Wall 4, while the plate 7 extends only to a point somedistance from the wall 3. In practice however, the plate 7 may alsoextend to the wall 3.

The lower wall 1, the plates 7 to 15 and the upper Wall 2 form, with thelongitudinal walls 5 and 6, compartments 21 to 30 within which theliquids flow. Each of compartments 21 to 30 communicates on each sidewith the compartments adjacent thereto, except that on the side of thewall 4 compartment 29 communicates only with the compartment which issituated below, i.e., with compartment 28. It does not communicate withthe compartment which is situated above, i.e., compartment 30. If theplate 7 extends to against the transverse wall 3, compartment 22 on theside of said transverse wall 3 communicates, in that case, only withcompartment 23 which is situated above. It does not communicate withcompartment 21 which is situated below. At any rate, even if the plate 7does not extend to the transverse wall 3, as is the case as shown inFIG. 1, no fluid stream is produced in the passage which remains openbetween the plate 7 and the transverse wall 3. This is due to the factthat the heavier liquid of compartment 21 does not rise through saidpassage and the lighter liquid introduced into the compartment 22 doesnot flow down through said passage. This is further describedhereinafter.

The compartment 21 is intended to contain dilute alcohol for carryingsoaps away without said alcohol being mixed with miscella. To this end,the transverse wall 3 has a discharge opening 31 at the level of thecompartment 21. Similarly, compartment 30 is intended to withdraw washedmiscella without the latter being mixed with the alcohol. To this end,the transverse wall 4 has a discharge opening 32 at the level of theupper compartment 30. It is to be noted that the dilute alcoholconstitutes the heavier liquid and that the miscella constitutes thelighter liquid. The light liquid, i.e., miscella, is admitted into thevessel through an inlet opening 33 provided in the transverse wall 3 atthe level of the lower portion of compartment 22. The heavy liquid,i.e., dilute alcohol, is admitted into the vessel through the inletopening 34 provided in the transverse wall 14 at the level of the upperportion of compartment 29. The light liquid obviously tends to rise intothe vessel, while the heavy liquid tends to flow down into the vessel.Thus an overall countercurrent effect is produced. However, in each ofthe intermediate compartments, i.e. in each compartment 22 to 29, meansare provided which mix intimately the two liquids entering thecompartment and which in addition propel said liquid mixture through thecompartments. Said means are comprised of rotating stirrers designatedby 35 in FIG. 1 and shown in detail in FIGS. 2 and 3.

Said rotating stirrers are arranged in the compartments 22 to 29 on thesides thereof. The side on which the stirrers are located comprise thosewith flanges 16 and 18, or 16 and 17, or 17 and 19 which are opposite.The side of the compartment where the rotating stirrer 35 is provided isalways the entry side of the compartment. This is due to the fact thatthe stirrers, as further described hereinafter, propel the liquids mixedin the compartment to the other end of the compartment.

Each of the stirrers 35 com rises a shaft comprised of a hollow centralpart 36, a spindle 37 and a solid part 38 forming spindle at the otherend. The shaft extends in transverse direction of the vessel and thehollow part 36 extends from the longitudinal wall to the longitudinalwall 6. Said hollow part 36 has four blades 39 arranged in planespassing through the geometrical axis 20 of the shaft, said bladesforming angles of 90 between them. Said blades 39 extend from the hollowpart 36 of the shaft to some distance from the plates delimiting thecompartment involved. FIGS. 2 and 3 relating to compartment 24, theplates involved are plates 9 and 10. The hollow part of the shaft is ina chamber 40 formed by sheets 41 and 42 bound to the plates 9 and 10. Onthe side of the flange 17, the sheet 41 has a flange 43 parallel to saidflange 17, and the sheet 42 comprises a flange 44 parallel to flange 16on the side of the latter. The sum of the heights of the flanges 43 and44 is less than the distance between sheets 41 and 42 and also the sumof the heights of the flanges 16 and 17 is less than the distancebetween plates 9 and 10. A passage thus remains free, on the one hand,between flanges 16 and 17 of the 4 plates 10 and 9 and, on the otherhand, between flanges 43 and 44 of sheets 41 and 42.

On the compartment side, sheet 41 comprises a vertical flange 45 havinga horizontally curved end 46. Sheet 42 comprises a vertical flange 47. Apassage remains free between the curved end 46 of the flange 45 and thelower edge 48 of the flange 47. The flange 45 is offset towards thecompartment with respect to flange 47 The direction of rotation of theshaft is indicated by arrow 49. The flanges 16 and 17 and the flanges 43and 44 form a double wall of the chamber 40, said double wall havingmedian slots 50 and 51. The flanges 45 and 47 form another walldelimiting the chamber 40 on the compartment side and having also amedian slot 52. The flange 45 forms the lower part of the wall.

Each of the intermediate compartments 22 to 29 contains on the shaftside a horizontal partition 53 extending in transverse direction andconnected to transverse wall 3 or 4 situated on the mixing device side.In longitudinal direction, the partition 53 extends into the compartmentto a point close to the mixing device, i.e., to a location between thepassage 51 of flanges 43 and 44 and the passage 50 of flanges 16 and 17.The passage 50 is thus divided into an upper portion and a lowerportion.

Outside the vessel, a second wall 54 is provided near the longitudinalwall 5. Similarly, along the longitudinal wall 6, a second longitudinalwall 55 is provided outside the vessel. The assemblies of said walls 5and 54, on the one hand, and 6 and 55, on the other hand, contain theshaft bearings.

The support 56 of the spindle 37 is entered into a tube 57 welded towalls 54 and 5. The spindle 37 is surrounded by the jacket 58 supportedby the barrel 59 accommodated in the support 56. The barrel 59 is fixedto the support 56 by a screw 60 the head of which bears on the washer67. The collar 61 of the support 56 is fixed to the wall 54 by screws 62and nuts 63; the head of the screws 62 maintains a washer 64 against thecollar 61 of the support 56. A ring 92 ensures the sealing be tween thewall 54 and the collar 61 of the support 56. The latter is provided witha central opening receiving the spindle 37 of the shaft. Said opening isnormally closed by a plug 65 with threaded rod, said plug maintainingthe washer 66 against the support 56.

The solid part 38 of the shaft is carried by the support 68 fixed to thewall 55 by means of screws 69 and nuts 70. The head of each screw 69maintains a washer 71 against the collar 72 of the support 68. A joint73 ensures the sealing between the wall 55 and the collar 72 of thesupport 68. The latter comprises a cylindrical end 74 mounted in thetube 75 which is welded to the wall 6 and to the wall 55. The outsideend of the solid part of the shaft 38 is supported by the bearing 76which is mounted in the collar 77 forming part of the support 68. Acover 78 retains the bearing and is fixed in turn to the collar 77 bymeans of screws 79 which maintain washers 80 against the flange 81 ofthe cover 78. Rings 82 and 83 provide the sealing between the part 38 ofthe shaft, on the one hand, the support 68 and the cover 78, on theother hand. The bearing 76 is thus mounted in a sealed area.

The sealing between the solid part 38 of the shaft and the cylindricalend 74 of the support 68 is ensured by glands 84 which are pressedagainst the flange 85 of the cylindrical end 74 of the support 68 by thestuffing-box 86 fixed to the wall 55 by means of screws 87 and nuts 88.The washers 89 are retained between the heads of the screws 87 and thestuffing-box 86. By a device not shown in the figures, the shaft isrotated in the direction of the arrow 49 of FIG. 3. Through the movementof the blades 39, an intimate mixture of the two liquids entering thechamber 40 is thus formed and the liquids are propelled out of thechamber 40 through the passage 52 due to the offset between the flange45 and the flange 5. 47 and due to the presence of a curved part 46 ofthe flange 45.

The dilute alcohol admitted through opening 34 in the compartment 29enters the chamber 40 of said compartment through the passages 50 and51. Simultaneously, the light liquid, i.e. miscella, coming fromcompartment 28 rises to compartment 29 and is directed by partition 53through the lower part of the pasasge 50 and through the passage 51 intothe same chamber 40 of compartment 29. In this chamber 40, the dilutealcohol and the light liquid coming from compartment are intimatelymixed due to the movement of the blades 39 and are propelled as amixture through compartment 29 in the direction of the arrows 90. Themiscella entering the compartment 29 is already partially washed whenpassing through compartments 22 to 28 from the inlet opening 33.

Under gravity, a decantation proceeds in compartment 29 and, at theoutlet from the latter, the washed miscella, forming the lighter phase,will ocupy the upper part of compartment 29, while the alcohol alreadypartially loaded with soap, which forms the heavier phase, will occupythe lower part of the same compartment 29. The washed miscella comingout of compartment 29 will flow through compartment 30 towards theoutlet 32 of the apparatus. On the other hand, the alcohol containingsoap coming from compartment 29 will come down and will be directed bypartition 53 of compartment 28 through passages 50-51 into the chamber40 of compartment 28. The alcohol entering the chamber 40 of compartment28 is mixed therein by means of blades 39 of the stirrer of saidcompartment with the partially washed miscella rising from compartment27 and directed by partition 53 through the lower part of passage 50 andthe passage 51 into the same chamber 40. At the inlet to compartment 28,an intimate mixture is produced, said mixture comprising the miscellaalready partially washed in compartment 27 and the alcohol alreadypartially loaded with soap coming from compartment 29. The mixture thusproduced at the inlet to compartment 23 will be propelled in thedirection of arrows 91 towards the outlet of compartment 28 where thepartially washed miscella will be supplied, as described above, to theinlet of compartment 29, while the alcohol containing soap will besupplied to the inlet of compartment 27.

Thus, from one compartment to another, the alcohol will progressivleybecome more concentrated with soap, while the miscella is more and morefreed from soap. The alcohol layer coming out from compartment 23 andsupplied to the inlet of compartment 22 is mixed therein with not yettreated miscella supplied through opening 33. The miscella which istreated in compartment 22 is discharged towards compartment 23 at theoutlet from compartment 22 where the alcohol loaded with soap comes downtowards compartment 21 through which said alcohol loaded with soap isdirected towards the discharge opening 31.

In the whole operation, miscella is thus treated in counter-currentfashion by dilute alcohol, while in each compartment the paths of thetwo liquids to be separated are in parallel relationship and along thesame direction, which prevents any turbulence and any parasiticrecycling in closed circuit.

The various compartments may have a very low height, for instance 50 to100 mm., which permits within a very limited space a multi-stage column.The room taken by the apparatus is thus much reduced and the erection ofthe apparatus is very inexpensive. The inactive volume of the liquids isalso much reduced due to the small room taken by the apparatus, and theoperating rate is very high.

What I claim is:

l. An apparatus for contacting two liquids of different specific weightsso as to carry out a procedure of solvent extraction comprising asubstantially rectangular vessel having four substantially verticalwalls, two of said walls extending in a first direction and theremaining two walls extending in a second direction which isperpendicular to the first direction, said vessel having a plurality ofsubstantially parallel and horizontal plates delimiting a series ofcompartments within said vessel, the said plates extending to the wallsof said vessel which extend in said first direction and extending to apoint spaced from the walls which extend in the second direction thusdefining a passage permitting the flow of liquids between the edge ofeach of the parallel plates and the walls extending in the seconddirection, the lower compartment of said vessell having a dischargeopening, the upper compartment of said vesel having a discharge opening,the compartment of said vessel immediately above the lower compartmenthaving an inlet opening situated on the same side as the dischargeopening of said lower compartment, the compartment of said vesselimmediately below the upper compartment having an inlet opening situatedon the same side as the discharge opening of said upper compartment,each of the intermediate compartments having a chamber delimited by twovertical walls which walls extend the whole height of the compartment,are parallel to said second direction, and each of the vertical wallsdelimiting said chambers having a median slot extending in said seconddirection over the entire width of the vessel, said chambers beingalternately arranged on one end and on the other end of thecompartments, the chamber of the compartment which is directly above thelower compartment being situated on the end of the inlet opening of saidcompartment and the chamber of the compartment which is directly belowthe upper compartment being situated on the end of the inlet opening ofsaid compartment, the portion of the chamber wall which is located onthe compartment side of the chamber and which is below the median slotbeing offset towards the compartment with respect to the upper part ofthe same wall and in addition having a flange which is bent toward theinside of the chamber, each of said chambers being provided with arotatable shaft, said shafts extending in said second direction andhaving blades attached thereto said blades lying in planes which extendthrough and include the geometrical axis of the shaft, a horizontalpartition lying in said second direction and extending into each of saidchambers from the wall of the vessel which extends in the seconddirection through the median slot in said chamber wall adjacent saidlast mentioned vessel wall.

2. An apparatus as claimed in claim 1, wherein the said chamber containsan additional vertical wall between the wall of the chamber containingthe median slot through which the horizontal partition extends and theshaft, said wall extending the whole height of the chamber and having amedian slot extending in said second direction over the entire width ofthe vessel, the said horizontal partition extending only through themedian slot of the chamber wall which is in the closest proximity to thevessel wall from which the horizontal partition extends.

References Cited by the Examiner UNITED STATES PATENTS 2,201,550 5/1940Van Dijck 23270 X 2,775,543 12/1956 Carver 23270.5 X 2,777,758 1/1957Pokorny 23270.5 3,032,403 5/1962 Kohl 23-2705 FOREIGN PATENTS 772,060 4/1957 Great Britain.

NORMAN YUDKOFF, Primary Examiner.

S. EMORY, Assistant Examiner.

1. AN APPARATUS FRO CONTACTING TWO LIQUIDS OF DIFFERENT SPECIFIC WEIGHTSSO AS TO CARRY OUT A PROCEDURE OF SOLVENT EXTRACTION COMPRISING ASUBSTANTIALLY RECTANGULAR VESSEL HAVING FOUR SUBSTANTIALLY VERTICALWALLS, TWO OF SAID WALLS EXTENDING IN A FIRST DIRECTION AND THEREMAINING TWO WALLS EXTENDING IN A SECOND DIRECTION WHICH ISPERPENDICULAR TO THE FIRST DIRECTION, SAID VESSEL HAVING A PLURALITY OFSUBSTANTIALLY PARALLEL AND HORIZONTAL PLATES DELIMITING A SERIES OFCOMPARTMENTS WITHIN SAID VESSEL, THE SAID PLATES EXTENDING TO THE WALLSOF SAID VESSEL WHICH EXTEND IN SAID FIRST DIRECTION AND EXTENDING TO APOINT SPACED FROM THE WALLS WHICH EXTEND IN THE SECOND DIRECTION THUSDEFINING A PASSAGE PERMITTING THE FLOW OF LIQUIDS BETWEEN THE EDGE OFEACH OF THE PARALLEL PLATES AND THE WALLS EXTENDING IN THE SECONDDIRECTION, THE LOWER COMPARTMENT OF SAID VESSELL HAVING A DISCHARGEOPENING, THE UPPER COMPARTMENT OF SAID VESSEL HAVING A DISCHARGEOPENING, THE COMPARTMENT OF SAID VESSEL IMMEDIATELY ABOVE THE LOWERCOMPARTMENT HAVING AN INLET OPENING SITUATED ON THE SAME SIDE AS THEDISCHARGE OPENING OF SAID LOWER COMPARTMENT, THE COMPARTMENT OF SAIDVESSEL IMMEDIATELY BELOW THE UPPER COMPARTMENT HAVING AN INLET OPENINGSITUATED ON THE SAME SIDE AS THE DISCHARGE OPENING OF SAID UPPERCONPARTMENT, EACH OF THE INTERMEDIATE COMPARTMENTS HAVING A CHAMBERDELIMITED BY TWO VERTICAL WALLS WHICH WALLS EXTEND THE WHOLE HEIGHT OFTHE COMPARTMENT, ARE PARALLEL TO SAID SECOND DIRECTION, SAND EACH OF THEVERTICAL WALLS DELIMITING SAID CHAMBERS HAVING A MEDIAN SLOT EXTENDINGIN SAID SECOND DIRECTION OVER THE ENTRIE WIDTH OF THE VESSEL, SAIDCHAMBERS BEING ALTERNATELY ARRANGED ON ONE END AND ON THE OTHER END OFTHE COMPARTMENTS, THE CHAMBER OF THE COMPARTMENTS WHICH IS DIRECTLYABOVE THE LOWER COMPARTMENT BEING SITUATED ON THE END OF THE INLETOPENING OF SAID COMPARTMENT AND THE CHAMBER OF THE COMPARTMENT WHICH ISDIRECTLY BELOW THE UPPER COMPARTMENT BEING SITUATED ON THE END OF THEINLET OPENING OF SAID COMPARTMENT, THE PORTION OF THE CHAMBER WALL WHICHIS LOCATED ON THE COMPARTMENT SIDE OF THE CHAMBER AND WHICH IS BELOW THEMEDIAN SLOT BEING OFFSET TOWARDS THE COMPARTMENT WITH RESPECT TO THEUPPER PART OF THE SAME WALL AND IN ADDITION HAVING A FLANGE WHICH ISBENT TOWARD THE INSIDE OF THE CHAMBER, EACH OF SAID CHAMBERS BEINGPROVIDED WITH A ROTATABLE SHAFT, SAID SHAFTS EXTENDING IN SAID SECONDDIRECTION AND HAVING BLADES ATTACHED THERETO SAID BLADES LYING IN PLANESWHICH EXTEND THROUGH AND INCLUDE THE GEOMETRICAL AXIS OF THE SHAFT, AHORIZONTAL PARTITION LYING IN SAID SECOND DIRECTION AND EXTENDING INTOEACH OF SAID CHAMBERS FROM THE WALL OF THE VESSEL WHICH EXTENDS IN THESECOND DIRECTION THROUGH THE MEDIAN SLOT IN SAID CHAMBER WALL ADJACENTSAID LAST MENTIONED VESSEL WALL.